The present invention relates generally to agricultural harvesters and, more specifically, to a feedrate control responsive to harvester tilt.
Throughput of a combine or similar crop harvesting device is typically maintained in a range that maximizes productivity while keeping one or more harvesting quality variables, such as grain loss or damage, at levels that are acceptable to the operator. Increasing harvester speed increases throughput, and as throughput increases, grain loss usually increases also. Various devices are available to sense the amount of material entering the feeder house or threshing and separating assembly of a combine and change the speed of the combine in response to changes in material to maintain a generally constant throughput. On a combine, throughput can be estimated by measuring actuator pressure of the variable drive that powers the rotor. Rotor variable drive actuator pressure (RVDAP) is a function of the feedrate, and feedrate tends to remain generally constant with constant RVDAP. By adjusting forward harvest speed to maintain a target RVDAP, productivity of the combine can be optimized. Such a device is described in copending and commonly assigned U.S. patent application Ser. No. 09/812,651 titled THROUGHPUT CONTROL FOR COMBINES filed on Mar 20, 2001. The target RVDAP can be modified if a harvesting quality variable differs from a desired quality target range over an extended period of time. For example, if target grain loss is exceeded for a period of time while operating at a target RVDAP, the target RVDAP will be reduced to decrease grain loss. In another copending and commonly assigned application, Ser. No. 09/918,266 entitled HARVESTER SPEED CONTROL WITH HEADER POSITION INPUT and filed Jul. 30, 2001, a conventional speed control controls harvester speed as a function of outputs of one or more sensors including a throughput sensor located downstream of the header. However, when the header is lowered., combine speed is immediately lowered to prevent a sudden increase in material downstream of the feeder housing input.
Although such systems as described above provide improved automatic control to increase harvester productivity and reduce operator fatigue, problems still exist with increased grain loss when the harvester is tilted from an upright position while operating on slopes. For example, a combine is designed to operate at highest efficiency when harvesting crop while level. As the combine tilts from the upright position on slopes, efficiency decreases and grain losses can increase significantly. Although grain loss on slopes can be reduced by slowing the combine, often the operator cannot properly estimate slope angles and anticipate sidehill losses. As a result, it is not uncommon for the operator to slow the machine much more than is necessary to maintain grain loss at target levels so that machine productivity is reduced and grain damage is increased. If the operator does not sufficiently reduce speed for the degree of slope, grain losses will exceed the target levels.
It is therefore an object of the present invention to provide an improved feedrate control system for a combine or other harvester. It is a further object to provide such a system which overcomes most or all of the aforementioned problems.
It is another object of the invention to provide such a harvester feedrate control system which reduces the problems associated with harvesting on sloping ground surfaces. It is another object to provide such a system that improves harvester productivity and reduces grain loss or damage when the harvester is operating in a non-level condition.
It is yet another object of the invention to provide an improved harvester throughput control system wherein harvester throughput is automatically adjusted according to machine slope. It is a further object to provide such a system which automatically maintains maximum feedrate at the desired loss level for improved productivity and reduced grain loss and damage. It is another object to provide such a control which is sensitive to both side hill and up and down hill slopes and which learns the relationship between loss and throughput as a function of machine tilt.
The system for improved harvester throughput control on slopes includes a combine tilt sensor sensing uphill, downhill and sidehill slopes. The output of the tilt sensor is connected to a processor which correlates losses indicated by grain loss sensors on the combine with tilt angle and throughput. An automatic feedrate controller compensates for machine tilt angle by adjusting the feedrate to maintain the desired loss level. In one embodiment, the tilt sensor is integrated directly into the feedrate controller to avoid the expense of an external sensor, a separate enclosure and a wiring harness.
Combine speed adjustments are normally controlled by a speed control as a function of outputs of one or more sensors including a throughput sensor located downstream of the header and harvest quality sensors such as grain loss transducers. However, if the tilt sensor indicates that the combine is angled from a level position, the speed is automatically lowered to prevent grain losses from increasing above the target level. The control continuously learns tilt angle, loss and throughput correlation to accommodate changes in settings and operating conditions. The speed reduction is selected based upon the learned correlation. As the slope decreases and the combine approaches a level condition, normal speed control is resumed. In the preferred embodiment, throughput is estimated utilizing RVDAP, and a target RVDAP is modified for short periods of time according to the learned correlation with tilt.
The system relieves the operator of the difficult task of estimating slope angles and anticipating losses caused by machine tilt. The machine is slowed only as much as necessary to maintain grain loss at target levels so that machine productivity is increased and grain damage from underutilized capacity is reduced. Excessive grain loss resulting from insufficient machine slowing is also avoided. Necessary speed compensation is automatically provided for uphill and downhill slopes and side to side slopes. The continuous learning process optimizes speed changes to keep the quality variable within desired limits and maintain harvester productivity, even when combine settings and harvest conditions change.
These and other objects, features ,and advantages of the present invention will become apparent to one skilled in the art upon reading the following detailed description in view of the drawings.